The research program seeks to bridge the gap between the study of human brain processes utilizing scalp-recorded electrophysiologic data, and neurophysiologic analyses at the cellular level which must be carried out in experimental animals. Analyses of the scalp topography of potentials associated with sensory, motor and cognitive processes in human subjects are compared with detailed surface and intracranial recordings of field potentials and cellular firing patterns in monkeys obtained under similar experimental conditions. The animal studies will identify and characterize the neural processes that are manifested as field potentials at the surface of the brain. Computations of the second spatial derivative of field potentials will be employed as an estimate of current source density (CSD). The current sources and sinks revealed by this procedure will be related to the laminar intracortical pattern of multiple unit activity (MUR). Event related potentials (ERP) associated with processing of tones and human speech sounds, with passive presentation of patterned visual stimuli as contrasted to activity associated with active scanning, and in tasks requiring self-initiated voluntary movements and the discrimination of auditory and visual stimuli will be studied. The human studies will be carried out within a developmental framework to trace the regional maturation of ERP from birth. These investigations are intended to provide information on the sequences of cerebral neural activity which underlie these sensorimotor processes in man, as well as to provide a foundation for the effective use of scalp-recorded event-related potentials in clinical applications which requires information on the sources of these potentials.